The present invention relates generally to tools and appliances used in geological-engineering prospecting and is particularly concerned with devices for soil sampling under water layer.
The invention can be most advantageously used for sampling subwater soil situated at a depth of the order of dozens of metres.
The soil sampler made according to the present invention is applicable in geological surveying within the shelf zone, i.e., a subwater projection of a continent.
Known in prior art are devices for soil sampling under water layer, comprising an air-operated percussion mechanism carrying a soil sampling socket arranged coaxially therewith.
The percussion mechanism comprises a housing which accommodates a cylinder with a piston travelling therein and serving as the striker of the mechanism. A passage is defined between the cylinder outer surface and the housing inner surface, said passage communicating with a pipe connection provided at the top of the housing and communicated with a piping made as a flexible hose. The other end of said hose is connected to a source of compressed air.
The striker is adapted to establish chambers in the housing, said chambers alternatively communicating with said passage for admission of compressed air thereto.
To alternatively communicate said chambers with the passage, provision is made in the cylinder for top and bottom ports the striker overruns during its reciprocation under the action of compressed air admitted to pass into said chambers.
To discharge used-up air from the cylinder chambers, the latter are communicated with the ambient atmosphere through another passage and a pipe connection joined therewith. Said pipe connection (in fact, an air outlet) is mounted at the top of the housing and made as a curved down pipe, wherein a check valve is provided. While performing the working stroke the striker acts upon the socket to sink it into soil (cf., e.g., USSR Inventor's Certificate No. 169461, Cl. E21b, 25/00).
The afore-discussed known devices are adapted for soil sampling under relatively inconsiderable water layer and cannot be used for soil sampling from the bottom of water basins as deep as over few scores of metres.
As the piping is made as a flexible hose, when it is submerged for a depth at which hydrostatic pressure exceeds the pressure of compressed air source, the hose is liable to contort and obstruct air admission into the passage of the housing and into the cylinder chambers to actuate the striker which renders the whole device unserviceable at reasonably great depths.
In order to prevent the hose from contortion and failure the pressure of the source of compressed air has to be increased which leads to higher operational costs of such devices.